Stripline filters include striplines formed on a dielectric substrate. A type of stripline filters includes a dielectric substrate, a grounding electrode, input/output electrodes, principal-surface lines, and side-surface lines (for example, see PTL 1). The grounding electrode and the input/output electrodes are disposed on a land of a set substrate. The principal-surface lines are disposed opposite the grounding electrode. Some of the side-surface lines and the principal-surface lines form resonant lines. In addition, some of the side-surface lines allow tap coupling between the input/output electrodes and the principal-surface lines.
PTL 1: WO2008/038443